In the practice of percutaneous coronary intervention (PCI), drug-eluting stents (DES) have become the de facto standard of care in the U.S. However, an intense controversy has emerged as it now appears that DES may significantly increase the late risk of stent thrombosis and all-cause mortality. This disturbing, yet unsubstantiated signal of compromised safety represents a potentially huge public health burden. Since initial approval of DES by the Food and Drug Administration (FDA) in 2003, approximately one million patients in the US alone are treated annually with DES. Thus, even a small excess relative risk, if confirmed, could translate to hundreds if not thousands of excess deaths each year. Therefore, to better understand and provide information about the safety and effectiveness of DES, we propose to extend the follow-up (to 5 full years) of 4,290 recent PCI-treated patients (2004- 2006) from the ongoing National Heart, Lung, and Blood Institute (NHLBI) Dynamic PCI Registry. This effort, coupled with existing long-term follow-up data of Dynamic Registry patients treated with bare-metal stents (BMS), will allow for a long-term evaluation of DES versus BMS in 'real-world'clinical practice. Importantly, this evaluation is not possible with extended follow-up of patients enrolled in the randomized clinical trials that led to FDA approval of DES because up to 60% of DES use today occurs in 'off-label'circumstances. Overall, the research aims are to: (1) Compare 5-year mortality and myocardial infarction between patients treated with DES versus BMS overall, within 'high-risk'subgroups, and by 'off-label'stent use;(2) Evaluate cardiac and non-cardiac causes of mortality among patients treated with DES versus BMS;(3) Compare 5-year mortality and repeat revascularization by the sirolimus-eluting versus paclitaxel-eluting stent overall, within 'high-risk'subgroups, and by 'off-label'stent use;and (4) Investigate mechanisms that contribute to stent thrombosis, myocardial infarction, death, and repeat revascularization in patients treated with BMS and DES. In summary, by extending the active NHLBI Dynamic Registry, we propose to analyze long- term outcome data on several thousand PCI patients treated with BMS and DES. This effort will permit an objective and timely real world evaluation of whether the recent signal of a possible mortality hazard associated with use of DES is real, and whether the recent widespread adoption of DES into clinical practice needs to be significantly altered.